This invention relates to a scroll fluid apparatus suitable for use as air compressor, refrigerant compressor, expander, hydraulic pump, etc.
Scroll fluid apparatus are disclosed in a number of patents including U.S. Pat. Nos. 3,884,599, 3,994,636 and 3,874,827, for example, and each have a pair of scroll members, each scroll member including an end plate and a wrap located thereon in upstanding position and one of the scroll members orbiting around the other scroll member while being prevented from apparently rotating on its own axis, to cause movable pockets defined between the two scroll members to undergo changes in volume. However, there are no reports in the literature of the prior art on proposals that have ever been made to minimize the moment of load applied to bearings for journaling a crankshaft for rotation.
Let us discuss this problem in some detail. A crankshaft is journaled by at least two bearings axially spaced apart from each other. Meanwhile the orbiting scroll member and the crankshaft are in engagement with each other outside the bearings. Thus the orbiting scroll member is supported in overhanging relation to the crankshaft. This means that the point of application of rotary force transmitted from the crankshaft to the orbiting scroll member and also from the orbiting scroll member to the crankshaft is disposed beyond the positions of the bearings. This gives rise to a moment of high magnitude which is the product of the transmitted force as multiplied by the distance at which the orbiting scroll member overhangs the crankshaft.